Inventories (Details) $ in Thousands, bu in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2020 USD ($)	Sep. 30, 2020 USD ($) bu	Sep. 30, 2019 USD ($) bu	Dec. 31, 2019 USD ($) bu
Inventory [Line Items]
Grain and other agricultural products		$ 557,808	$ 560,626	$ 907,482
Frac sand and propane		10,064	14,592	15,438
Ethanol and co-products		59,543	26,218	95,432
Plant nutrients and cob products		120,173	133,839	146,164
Railcar repair parts		7,016	5,811	6,020
Total inventories		$ 754,604	$ 741,086	$ 1,170,536
Bushels of grain held in storage for others and excluded from inventory calculations | bu		2.3	2.7	6.4
Inventory write down		$ 10,933	$ 0
RMI
Inventory [Line Items]
Grain and other agricultural products		512,900	488,200	$ 852,600
Ethanol and co-products		10,400	$ 12,600	$ 10,600
COVID-19 Pandemic
Inventory [Line Items]
Inventory write down	$ 10,600	$ 10,900